1. Field of the Invention
The present invention relates to an edge joint welding device in which, to a bonding position on an end surface portion in an edge of a layered base material, a laser beam is emitted from a laser beam emitting head that faces the end surface.
2. Description of the Related Art
YAG laser welding has characteristics described below and has been widely employed in automatic welding, such as for automobiles.
(1) Convergent laser light can be produced and low distortion and high speed welding are possible.
(2) Since the laser light absorption factor thereof in a metal material is several times that of a CO2 laser beam, high efficiency welding is possible. Furthermore, since the wavelength is one-tenth that of a CO2 laser beam, it is not significantly influenced by plasma generated during welding.
(3) Since laser light can be transmitted by means of a flexible optical fiber, manipulation is easy and a multi-jointed robot can be utilized. Furthermore, it can be transmitted to a place up to about 100 m distant therefrom.
(4) Since in laser light, time sharing and power sharing are possible, by using it at a plurality of work stations, a high utilization efficiency can be obtained.
However, in YAG laser welding, although a laser beam is focused to increase energy density, thereby executing welding, since the focused light spot diameter is 0.3 to 1 mm, which is very small, in edge joint welding in which, to a bonding position on an end surface portion in an edge of a layered base material, a laser beam is emitted from a laser beam emitting head which faces the end surface, when uniting of the end surface portion is insufficient, that is, when there is a gap, since the laser beam passes through the end surface portion, the end surface cannot be welded. Laser beam emission positional divergence with respect to a bonding line of the layered base material is likely to occur. Thus, stable, highly reliable edge joint welding is difficult.